Telephone-exchange system



Dec. 18, 1923.

1,478,3? c. w. KECKLER TELEPHONE EXCHANGE SYS TEM /nve/7for.' Char/es W Keck/er."

Patented Dec. 18, 1923.

UNE E'EE SfiATES arisen enrr.--ir eases,

CHARLES V7. KECKLER, OF NEWARK, NEW JERSEY, ASSIGNOB TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF ITEW YORK, N. 1 A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed December 26, 1919. Serial No. 347,390.

To aZZ whom it may concern.

Be it known that 1, CHARLES WILLIAM KncxLE-n, a citizen of the United States, residing at Newark, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This inventicnrelates to telephone exchange systems and particularly to circuit arrangements for use at a private branch ex change when such an exchange is employed in connection with an automatic central oflice.

An object of the invention is to provide means for enabling a subscriber oi the private branch exchange system to rapidly es tablish connections over the trunks extendingto the central oifice without the aid of. the operator. j

In attaining the object of the is contemplated dividing the subscribers lines terminating normally in jacks at a manual exchange into groups, ,each group having access to a group of trunk lines extending from the private branch exchange to the automatic exchange. For example, in a private branch exchange system of 100 subscribers lines and 15 trunk lines, there might be five groups of subscribers lines of 20 lines each, each group having access to a. group of 3 trunks extending to the automatic exchange. Each subscribers station is provided with switching means whereby his line may be extended at will to the manual switchboard in case a local connection is desired, or over a trunk line to the automatic exchange in case a station at that exchange is desired.

A further feature consists in the use of a novel relay arrangement associated with each trunk, whereby an idle trunk is preselected, such trunk being connected to a calling line upon the actuation of switching means at the calling subscribers station.

A further feature consists in the provision of means for extending a calling line over a trunk of another group in case 01" an overfiow, i. e., whenall trunks of the group, with invention it which said calling line is associated, are busy.

A still further feature rests in the p1'0 vision or" means for indicating to an operator in a system of this nature the trunks and subscribers lines which are busy.

Referring to the drawing which shows only so much of a telephone exchange sys tem as is necessary for a. comprehension of the invention; Fig. 1 shows two subscribers lines A and B, and three trunk lines D, E, and F with the apparatus therefor. The trunk lines D, E and F extend to an automatic exchange and terminate thereat in line or trunk finders diagrammatically indicated as L. Each line or trunk finder has access to automatic selectors (not shown) and connectors such as C. H represents the station of a subscriber in the automatic exchange; Fig. 2 shows diagrammatically a cord circuit K arrangedwith a sender S3 and may be of any well known type. For the sake of clearness only two subscribers stations A and B of the private branch exchange and three trunk lines D, E, and F terminating therein and extending to an automatic exchange are shown, it being obvious that five ten or twenty stations may be arranged to have access to the three trunks. It will also be obvious that a greater or lesser number of trunks, for example 2 or 5, may be grouped together.

Eachsubscribers line is provided with a sender S, which may be of any well known type and a non-locking key. Normally each subscribers line terminates in a jack in the private branch exchange. By removing the receiver from the switchhook aline is extended to the line jack and a signal individual to the jack is displayed, By removing the receivcr and actuating the nonlocking key a calling line will be automatically extended over an idle trunk to the automatic exchange. Each trunk is provided with a jack at the private branch exchange switchboard by means of which the operator may connect subscribefis line thereat with the trunk extending between the private branch exchange and the automatic exchange.

The invention will be more readily understood from a detailed description of the operation of the system. The party at substation A desiring to extend his line over one of a plurality of outgoing trunk circuits to the. automatic exchange depresses non: locking key 5 and removes his receiver from the switchhook which causes the operation of marginal relay 6 over the following path: ground, contacts of non-locking key 5, inner armature and back contact of relay 7, ring spring and contact of jack 8, winding of relay 6 and normal contacts of relay 9 to grounded battery. Relay 6 is then held up over a path including ground, normal contacts-of relay 10, front contact and outer right-hand armature of relay 6, ring spring and contact of jack 8, winding of relay 6, and normal contacts of relay 9 to grounded battery. Relay 6 upon energization completes a. parallel circuit for cut-off relay 7 and line busy signal 18 at its left-hand armature and front contact, and at its inner right-hand armature and frontcontact completes a circuit for connecting relay 12 of the trunk circuit over the following path: grounded battery, inner right-hand armature and: front contact of relay 6, left-hand armature and back contact of transfer relay it of the trunk circuit D and winding of connecting relay 12 of the trunk circuit D to ground. The lighting of line busy signal 18'associated with the line jack 8 of sub station A at the switchboard indicates to the operator that the line is busy and energization ofcut-ofi" relay 7 disconnects substation A from the jack 8, thus preventing interference from and the listening in of the operator. Connecting relay 12 upon energization establishes a circuit for transfer relay 51 of trunk D associated with station B, over the following path: ground, front contact and outer right-hand armature of relay 12, outer right-hand armature and back contact of connecting relay 52 and winding of relay 51 to grounded battery. It will be seen that the transfer relays associated with trunk D of all other stations would be energized in parallel with relay 51.

The transfer relays in operating prevent this trunk from being seized by other calling lines and render the next idle trunk selectable. Energization of. relay 51 completes a circuit for thetrunk busy signal 60 over a path including grounded battery, front contact and right-hand armature of relay 51, through signal 60 and the normal contacts of jack 64: to ground. Lamp 60 in lighting indicates to the operator that trunk D is in use. Connecting relay 12 in energizing extends the line of station A over the trunk to a trunk or line finder at the automatic exchange, which is diagrammatically indicated as L.

The equipment at the automatic exchange may be of any well known type in which the switches thereat are operated by interrupt mg a loop. There may be a number of selectors interposed between the line finder,

L and the connector C (diagrammatically indicated). 7 r 7 When the line of substation A is extended to the automatic exchange by the energization of connecting relay 12, relay 15 in series with the line, will be energized by current from the automatic exchange flowing through the loop of station A to ground at the automatic exchange. Relay 15 in energizing completes, at its armature and front contact, a circuit for slow-to-release relay 9. Cut-off relay '7, line busy signal 18 and connecting relay 12 are held energized through the alternate contacts of slow to release relay 9, the circuit for relay 6 being interrupted at the normal contacts of relay 9, upon the energization of relay 9. Relay 6 is thereupon deenergized.

The subscriber at station A now proceeds to operate the impulse sender S at his station to send out impulses in accordance with the number of the station desired at the automatic exchange. In response to these impulses the switches at the automatic, ex

change will be set upon the terminals of the desired line and the station such as H will be signalled in the manner well l nown. lVith each interruption in the line circuit of station A, the relay lothereon will be deenergized thereby opening the circuit of relay 9, but since it is of the slowto-release type its armature will not release during such time. 7

Upon completion of conversation the subscriber at station A restores the receiver to the switchhook, thus opening the loop to the automatic office and causing the switches thereat to return to normal. Relay 15 thereupon deenergizes, thus opening the circuit for relay 9, which in turn deenergizes and opens the circuit for line busy signal 18 and cut-off relay 7 and connecting relay 12. Relay 12 in deenergizing releases all transfer relays in trunk D and extinguishes lamp 60. The line is then ready for another call.

It will now be shown how substation B is automatically connected to the next idle trunk of the group with which it is associated, if the first trunk such as D is being used by one of the stations of the group such as A. If the subscriber at B depresses nonlocking key 40 and removes the receiver, marginal relay 46 operates over a path similar to that described for relay 6 of the line for station .A. Energization of relay 46 establishes a parallel circuit for cut-oft relay 47 and line busy signal 58. It will be remembered that when connecting relay 1?. of the first trunk was energized a circuit for transfer relay 51 of trunk D individual to station B was energized and in so doing retrace? prepared a circuit for the connecting relay 62 of the second trunk E of the group. Therefore if trunk D is busy when station B calls, connecting relay 62 of trunk E will be energized over a path extending from grounded battery, inner right-hand armature and front contact of relay e6, left-hand armature and front contact of relay 51, lefthand armature and back contact of transfer relay 61 of trunk E and the w iding of relay 62 to ground. Relay 62 will be held up over this path until slow-to-release relay 4-9 is energized, when it will be helc up over a path extending from ground, winding of relay 62, front contact and inner right-hand armature of relay 6:2 and alternate contacts of relay a9 to grounded battery. Connecting relay 62 in energizing completes a circuit for the transfer relays of all other lines associated with trunk E such as that for station A, over a path extending from ground, front contact and. outer right-hand armature of relay 62, outer right-hand armature and back contact of relay 22, and winding of relay 21 to grounded battery. Relay 21 upon energization completes a circuit for the busy signal 70, of trunk E over path extending from grounded battery, front contact and right-hand armature of relay 21, through trunk busy signal and normal contacts of jack 74 to ground. Signal '50 is thereupon displayed indicating to the operator that trunk E is in use.

Station B is now connected to trunk E and the sender S2 may be operated to set the switches at the automatic exchange and after completion of conversation and restoration of the receiver to the switchhook all relays and signals operated by station B will be restored to normal.

It will now be assumed that all trunks of -the oup to which stations-A and l) have g access are busy. Since as heretofore explained it is contemplated to have a plurality of groups of trunks with a plurality of subscribers to each group, it is unlikely that all trunks to the automatic exchar e will be busy at the same time. The circuits are therefore arranged so that if all the trunks of the group with which the subscriber of a particular group is associated, are busy, the call will be automatically routed to the operator where she may by means of a link circuit K connect the calling subscriber to an idle trunk of another group of trunks. If trunks I), E and F leading to the automatic exchange are busy when the (illscriber at station A. actuates the non-loci key 5 and removes his receiver, his line will be automatically connected to his line jack 8 and the line signal 14 individual to his line will be displayed. The operator noting the signal, will insert plug 2 of the cord circuit K, diagrammatically shown) and actuate a listening key (not shown) to inquire his wants. Upon being informed that a connection with an automatic exchange subscriber is desired, the operator inserts the calling plug 3 of cord circuit K into an idle trunk of another group of trunks leading to the automatic exchange and will either actuate dialing key l and her sender to call tne desired subscriber or permit subscriber A to call by actuating his sender S depending upon the instructions of the subscriber at station A. Only one group of trunks has been here shown with a. plurality of subscribers connected thereto and it will be assumed that there is a second group of trunks at the private branch exchange identical with that shown in Fig. 1 on the drawing.

It has been described how station E was automatically connected to trunk B when trunk D was in use by station A. In a similar manner a thiro station (not shown) would be automatically connected to trunk 1 if trunks D and E were in use. Assume that trunk l), E, and F are in use by stations not shown and subscriber A operates nonlocking key 5 and removes the receiver from the switchhook. In such case transfer relays ll, 21 and 31 individual to station A and associated with trunks D, E and F respectively would be operated. A path for the energization of re Kay 6 of station A may be traced as follows: ground, contacts of key 5, inner right-hand armature and back contact of relay 7, ring spring and contact of ack 8, winding of relay 6, normal contacts of relay 9 to grounded battery. Relay 6, thereupon energizes and is held up over a path including grounded battery, normal contacts of relay 9, winding of relay 6, ring spring and contacts of jack 8, inner armature and back contact of relay 7, through the substation loop, outer armature and back contact of relay 7, tip spring and contact of jack 8, right-hand winding of relay 10 to ground. Relay 10 has a high resistance winding and does not energize until the armature of relay 6 completes a circuit for relay 10 over the path extending from grounded battery, inner right-hand armature and front contact of relay 6, left hand armatures and front ontacts of transfer relays 11, 21 and 31 of trunks D, E and F respectively, and left-hand winding of relay 10 to ground. Relay 10 upon energize.- tion completes a circuit at its armature and front contact for line signal let causing said signal to be displayed until the operator answers.

The operator noting line signal l l inserts answering plug 2 of cord circuit K into jack 8, thus interrupting at the jack contacts, the circuit for line relay 10 which upon deenergizing interrupts the ircuit for line signal 14. The operator then actuates a listening key (not shown) and upon being informed by the subscriber that he desires to call a subscriber at the automatic exchange, the operator inserts plug 3 1nto a trunk jack of an idle trunk or another group.

It will be assumed that jack 84 of trunk F belongs to another group. Insertion of plug 3 into jack 84, establishes a paralel circuit for the energization of all transfer relays associated with trunk F over the following path: ground, alternate contacts of jack 84:, and'thence through the outer righthand armatures and back contacts of the connecting relays such as 32 and 72 and the windings of the transfer relays such as 81 and 71 to grounded battery. Energization of the transfer relays of trunk F opens the circuits of all connecting relays associated with trunk F at the left-hand armatures and back contacts of the transfer relays and prevents this trunk from being selected by a calling subscriber. Insertion of plug 3 in jack 84 established a loop for the switches in the automatic exchange causing the line or trunk finder thereat to operate in the manner well known. Subscriber A may now interrupt this loop by means of his sender and set the switches in the automatic exchange after which ringing current will be automatically sent out until the called subscriber responds. Upon completion of conversation and restoration of the receiver to the switchhook by the subscriber at station A the loop will be again interrupted and the switches at the automatic exchange will be restored to normal. By means of a supervisory signal (not shown) in the cord circuit K the operator will be informed that conversation is completed and will remove the plugs of the cord from their associated j aclzs when all relays will be restored to norma Assume that the subscriber at station A desires the operator, either to complete a connection with another station of the private branch exchange system or over a trunk circuit leading to the distant 'ofiice.

Removal of the receiver at station A from the switchhook causes energization of line relay 10 over the following path: ground right-hand winding of relay 10, tip spring and contact of jack 8, back contact and outer right-hand armature of relay '7, through the substation loop, inner armature and back contact of relay 7, ring spring and contact of jack 8, winding of relay 6, and normal contacts of relay 9 to grounded battery. Relay 6 is of the marginal type and will not energize in series with relay 10 due to the high resistance of the winding of relay 10. Relay 10 in energizing completes a circuit through its front contact and armature for line signal 14. The operator observing the signal 14 inserts lug 2 into jack 8 whereupon the circuit or relay 10 is interrupted at the contacts of jack 8, thereby deenergizing relay 10, which in turn causes line lamp i l to be extinguished. The operators listening key (not shown) is then actuated and having ascertained the number desired by the calling subscriber, the operator com storing all relays to normal and station A is ready for the next call.

Cord circuit K is provided with a sender S3 so that the operator may call the subscriber at the automatic exchange in case the subscriber at station A so desires.

What is claimed is:

'1. In a telephone exchange system, a manual exchange, an automatic exchange, a plurality of groups of trunk circuits extending from said manual to said automatic exchange, a plurality of groups of subscribers lines terminating in a switchboard at the manual exchange, each of said groups having access to a particular group of trunk circuits, means for enabling a calling subscriber at said manual exchange to extend his line to the automatic exchange over an idle trunk circuit of the group with which his line is associated without the aid of the operator, and means operating automatically to signal the operator to permit the line of a calling subscriber to be extended over an idle trunk circuit of another group of trunks if all the trunks of the group to which the calling subscriber has access are busy.

2. In a telephone exchange system, a manual exchange, an automatic exchange, a plurality of groups of trunk circuits extending from said manual to said automatic exchange, a plurality of groups of subscribers lines terminating at said manual exchange, each group having access to a. group of said trunk circuits, a line signal at said manual exchange for each of said subscribers lines, switching means for each subscribers line for actuation by the subscriber, means responsive to the actuation of said switching means for extending said line over said trunk to the automatic exchange, and means responsive to the actuation of said switching means for actuating said line signal if all trunk circuits of the group to which the line has access are busy.

3. In a telephone exchange system, a manual exchange, an automatic exchange, a plurality of trunk lines extending from said manual exchange to said automatic exchange, a plurality of subscribers lines normally connected to jacks at said manual exchange having access to said trunk lines, a busy signal for each line jack, switching means for each subscribers line, and relay means responsive tothe actuation of said switching means for seizing an idle trunk line, for disconnecting said line from its associated jack, anc for displaying the busy signal of the line.

4:. In a telephone exchange system, a manual exchange, an automatic exchange, a trunk circuit extending from said manual to said automatic exchange, a plurality of subscribers lines terminating at said manual exchange, a line relay, a jack and a line signal for each of said subsc-ribers lines, said subscribers lines being normally connected to said jacks, a key and a switchhook for each subscribers line to be actuated by the subscriber, means responsive to the actuation of said key and switchhook, for connecting said line with said trunk circuit and for disconnecting said line from said jack and means responsive to the actuation of said switchhook only for actuating said line signal.

5. In a telephone exchange system, a manual exchange, an automatic exchange, a plurality of groups of trunk circuits extending from said manual to said automatic ex change, a plurality of groups of subsoribers lines terminating at said manual exchange, each group of said lines having access to one of the groups of said trunk circuits, a line relay, a jack and a line signal for each of said subscribers lines, said subscribers lines being normally connected to said jacks, switching means actuated by the subscriber for each subscribers line, and means consisting of relays responsive to the actuation of said switching means for automatically connecting a subscribers line to an idle trunk of the group with which the line is associated and for disconnecting said line from said jack.

6. In a telephone exchange system, a manual exchange, an automatic exchange, a plurality of trunk circuits extending from said manual to said automatic exchange, a plurality of subscribers lines normally terminating in jacks at said manual exchange, a line relay and a line signal for each of said subscribers lines, switching means for each subscribers line adapted upon actuation to associate said line with an idle trunk circuit, and means for operating said line relay and displaying said line signal if all trunk circuits are busy.

7. In a telephone exchange system, a manual exchange, an automatic exchange, a plurality of subscribers lines normally terminating in jacks in a switchboard at said manual exchange, a plurality o1 trunk lines less in number than said subscribers lines accessible to said subscribers lines and extending between said exchanges, a nonnumerical selecting means associated with each subscribers line arranged to preselect idle trunks, said means including a connecting relay for each trunk, and means under the control of a callin' one of said subscribers lines for actuating one of said connecting relays thereby connecting said line to an idle trunk and disconnecting said line from said jack.

8. In a telephone exchange system, a plurality of subscribers lines, a plurality of trunk lines to which said subscribers lines have access, said trunk lines being less in number than said subscribers lines, a connecting relay for each subscribers line associated with each trunk adapted upon energization to connect a calling one of said subscribers lines with an idle trunk, a barring relay for each subscribers line associated with each trunk, and means under the control of the calling subscriber tor energizing said connecting relay.

9. In a telephone exchange system, a man ual exchange, an automatic exchange, a trunk circuit extending from said manual to said automatic exchange, a plurality of subscribers lines terminating at said manual exchange, a jack for each of said lines in which said lines normally terminate, switching means for each line to be actuated by the subscriber, means consisting of relays responsive to the actuation of said switching means for connecting said line with said trunk circuit and for disconnecting said line from said jack and means for each line for controlling switches of said automatic exchange over said trunk circuit.

10. In a telephone exchange system, a manual exchange, an automatic exchange, a trunk circuit extending from said manual to said automatic exchange, a plurality of subscribers lines terminating at said manual exchange, a jack for each of said lines, switching means for each line to be actuated by the subscriber, means consisting of relays responsive to the actuation of said switching means for controlling the connection of said line with said trunk circuit and with said jack and means for each line for controlling switches of said automatic exchange over said trunk circuit.

11. In a telephone exchange system, a manual exchange, an automatic exchange, a trunk circuit extending from said manual to said automatic exchange, a plurality of subscribers lines terminating at said manual exchange, a jack for each of said lines, switching means for each line to be actuated by the subscriber, a relay responsive to the actuation of said switching means for controlling the connection of said line with said trunk circuit and a second relay responsive to said switching means for controlling the connection of said line with said jack.

12. In a telephone exchange system, a plurality of subscribers lines, a plurality of trunk lines to which said subscribers lines have access, said trunk lines being less in number than said subscribers lines, a

connecting relay for each subscribers line gizing the connecting relays and the second assoclated W1th each trunk adapted upon relays. energlzation to connect a calhng one of sand In wltness whereof, I hereunto subscrlbe 1 subscribers lines with an idle trunk, a see my name this 19th day of December A. D 0nd relay for each trunk for use in prese- 1919. r lecting idle trunks and means under the 7 control of the calling subscribers for ener- CHARLES W. KE CKLER; 

